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Magnetic Mitigation MICE Partial Return Yoke

Magnetic Mitigation MICE Partial Return Yoke. Overview. Introduction Outcome of review meeting Comments and recommendations Effect of PRY on MICE Solenoids Update on PRY. Partial Return Yoke. Aim of PRY: Reduce stray field in hall to tolerable level Shielding plates wall thickness 10 cm

justina-pearson
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Magnetic Mitigation MICE Partial Return Yoke

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  1. Magnetic MitigationMICE Partial Return Yoke

  2. Overview • Introduction • Outcome of review meeting • Comments and recommendations • Effect of PRY on MICE Solenoids • Update on PRY

  3. Partial Return Yoke • Aim of PRY: Reduce stray field in hall to tolerable level • Shielding plates • wall thickness 10 cm • weight: 35t • Performance • Reduces stray field outside of shield to ≈10 Gauss • No PRY: 400 Gauss H Witte. Step IV & VI: Local Flux Return. MICE CM 34, October 2012. (Note: not to scale)

  4. Principle

  5. Partial Return Yoke Shielding plates 8m 3m Support Structure Courtesy of Jason Tarrant / Steve Plate

  6. Review Meeting • 23rd/24th of September • Presented solution: Partial Return Yoke • Findings • Recognition: intensive programmeof FE modelling • The team is to be congratulated on the effort that has gone into this work • The design of the PRY shielding and the procedure for installation are basically sound • The strategy of improving the shielding now to reduce the risk of losing running time later is sound • The ISIS Group is satisfied with the work being done by the MICE Collaboration to control the level of stray field

  7. Recommendations • Platform on the north side of the experiment • Ensure that PRY does not increase risk of coil failure • Forces and coil quenches • Modify PRY: independent of mezzanine • Compatibility of PRY with Step VI • Commissioning plan for Step IV • Validate results of Step IV with measurements • Steve Plate: UK visit • Watch schedule

  8. Effect of PRY on Solenoids • Quenches • Forces • Variation in material parameters • Offsets

  9. Effect of PRY on Quenches • Superconducting state: fct (B, J, T) • Effect of PRY: changes B • Simulation 1: • Step IV configuration with PRY • Simulation 2: • Extrusion coupling: use magnetization of Simulation 1 • No coil currents • Done for 240 MeV flip and solenoid mode • (MICE: NbTi, Cu:Sc = 4)

  10. Effect of PRY on Quenches B (T) 240 MeV Flip Mode Tracker 2 AFC Tracker 1 28.5 mT Spectrometer+End coil 2

  11. Effect of PRY on Quenches B (T) 240 MeV Solenoid Mode 23 mT End coil 2

  12. Tc End Coil 2 240 MeV Flip T(K) L. Bottura, “A practical fit for the critical surface of Nb–Ti”. DOI: 10.1109/77.828413

  13. ΔTc End Coil 2 ΔT(K) ΔTc < 0.02 K Assume ΔB of 30 mT everywhere

  14. Spectrometer Solenoid, B 240 MeV Flip B (T)

  15. Spectrometer Solenoid Note: steps due to Bisection method ΔTc < 0.02 K

  16. 240 MeV Solenoid, End Coil 2 Tc (K) ΔTc (K) ΔTc < 0.02 K

  17. Variation of Material Properties Half PRY Simulation Iron Air

  18. Magnetization 240 MeV Flip

  19. Half PRY Simulation Forces in Newton Fx PRY1 (Sol/Flip): Fx=19776 N / 52317 N Fy Acceptable force: 1/3 of longitudinal force (Tracker: 50 tons, FC: 20-30 tons)

  20. Flip Mode - Forces Opera 3D Offset Study

  21. PRY Geometry – Backing Plates Updated model, including centre section Slightly increased stray fields, but enough margin to compensate

  22. Residual Field

  23. Residual Field

  24. Engineering Center sections (independent removal) Courtesy of Steve Plate, BNL Previous design New design: Left/right symmetry Lowered Restraint bars (clear mezz, south) Add Hall floor (no leg splices, shorter leg) Shorter horizontal reach New leg arrangement

  25. Engineering Tie-down bar apertures repositioned Waveguide slots to be angled upward Crossbar positions not final

  26. Engineering 6-Section Design 1807 kg 3306 kg 1380 kg 3490 kg Lighter color indicates machined areas

  27. Things to do • Engineering • Recheck new model in ANSYS Workbench • Reposition crossbars / slots tracker waveguides • Detailing: tapped/drilled holes, … • Drawings • Simulations • Cross-check with Opera hall model • Verify forces on coils / PRY • End-to-end simulation

  28. Summary • Review: very positive feedback • MICE solenoids: not affected by PRY • Engineering suggestions: implemented / underway • Compatibility with Step VI

  29. Additional Slides

  30. Solenoid Mode - Forces

  31. Solenoid Mode

  32. Flip Mode

  33. Fabrication Cost & Procurement Status • JFE steel order (JFE, Kurashiki, Japan) • 100 mm thick main plates, 50 mm backing plates • Steel of magnetic uniformity • Material total ~$70,000 for 12 plates (8 end, 4 ctr, 8 backing plates) • Delivery: ~16 weeks • Machining • Separate vendor, to be identified • ~$2850, each plate • Framework drawings • Some dwgs. out for quotation • 3 suppliers queried • Awaiting responses

  34. Work to complete • Modifications to shielding plates • Reposition crossbars • Virostek plate extension mounts and flux leakage mitigation parts • Finalize position and size of slots for tracker waveguides (angled, not normal to surface) • Add drilled/tapped holes for bolted connections, hoist rings, crossbar mounts • Assembly and detail drawings for all of the above items • Deflection/Stress Analysis • Recheck new model in ANSYS Workbench • No surprises expected, but need verification • Structural Framework • Assembly and detail drawings for restraints bars & lower support arms

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